Troubleshooting guide

Troubleshooting SONET
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LOF Determination
The SONET port may not operate if a Loss of Frame (LOF) condition occurs. LOF
conditions occur when there is no valid framing pattern for 3 milliseconds.
When a LOF condition on a POS module port occurs, follow these steps to determine
the LOF condition:
1. Locate the SONET termination equipment.
2. To view the status of the SONET link, use the show controllers command in
Privileged EXEC mode, as shown in the following example:
BSR64000#show controllers pos <slot/port>
If the SONET link is down, the message
pos <slot>/<port> is down
appears.
3. View the Active Alarm field in the show controllers pos command output to
determine if there is an LOF failure on the POS module port.
4. If LEDs on the POS module are green but you suspect that the module has
transmission problems on a port (causing an LOF on the other SONET device’s
receive port), check if a L-AIS or L-RDI failure has occurred. To do so, view the
Active Defect field in the show controllers pos command output. An L-AIS and
L-RDI failure is generated by the other SONET device and sent out its transmit
port when a failure is detected on its receive port. An L-RDI can indicate an LOF
failure condition.
If there is no L-AIS or L-RDI alarm, the problem may be isolated to the other
SONET device.
LOF Resolution
Follow these steps to resolve an LOF condition once the cause or problem area is
isolated:
1. Ensure that the clock source on one terminal device is external or line and that the
other clock source on the other terminal device is internal.
2. Ensure that both terminal devices are operating at the same data rate; for example,
OC3 or OC12.